In the past, a titania nanocrystal has been developed and used in a variety of fields due to its characteristic of a high refractive index.
For example, a silicone resin used as an LED sealing material is excellent in terms of heat resistance and light-fastness, but has a low refractive index, and therefore there is a problem of low efficiency of extracting light from an LED. In order to solve this problem, it has been attempted to improve the refractive index by synthesizing a titania nanocrystal which has been made oleophilic by surface modification and producing a composite with a silicone resin (Patent Document 1).
In addition, a zirconia nanocrystal has been developed and used for a variety of uses, such as a hard coating agent of glass lenses and a polishing agent, due to its characteristics of high refractive index and high strength.
For example, a method of synthesizing a zirconia nanocrystal having high dispersibility in an organic solvent is known (Non-Patent Document 1 and Non-Patent Document 2).